ES2251031T3 - METHODS AND DEVICES FOR MEASURING THE TOTAL AMOUNT OF POLAR COMPOUNDS IN OILS IN DECOMPOSITION. - Google Patents

Abstract

This invention relates to methods for determining whether or not to discard a sample of oil based on the presence of polar compounds in the oil and devices to be used therewith. In a preferred embodiment a test strip comprising an adsorbent affixed to a backing is spotted with a polar indicator. A sample of oil is positioned on a heat conducting device supporting the test strip and the oil is allowed to migrate over the adsorbent material thereby displacing the polar indicator in an amount related to the amount of polar compounds in the oil. This displacement is correlated to the amount of polar compounds in the sample.

Description

Methods and devices for measuring quantity Total polar compounds in decaying oils.

Field of the Invention

The present invention relates to methods and to devices to identify the presence and quantify the quantity of polar compounds in oils that result from the rupture of oils from use or storage.

Background of the invention

When oils (used here to refer to oils, fats, butters and mixtures thereof) are heated in presence of oxygen and water, thermolytic reactions take place and oxidative, resulting in the degradation of oils. The most edible oils are triglycerides formed to from the reaction of fatty acids with glycerin. The oils are They generally consider non-polar in its pure form. But nevertheless, some oils contain from about 0.5% to about 2% of free fatty acids. The presence of these fatty acids can provide some polarity to fresh oils. However, to as these oils are heated at elevated temperatures (by example, in frying conditions or in high conditions shear and pressure, as can be found for some synthetic oils), the oils can be oxidized, polymerized and / or hydrolyze Oxidation can generate new functional groups in the triglyceride hydrocarbon chain, and hydrolysis can generate free fatty acids, monoglycerides and diglycerides. These processes can increase the polarity of oils.

In the literature there are a number of methods to detect degraded products in oils. Most methods are specific to a particular degradation path or test for a particular chemical change. For example, the measurement of free fatty acids in oil can be used to calculate the level of degradation of the oils by the hydrolysis route. This method does not quantify total polar compounds in oils. Other methods for assessing oil degradation include, but are not limited to, the determination of the number of hydroxyls, the iodine index, the carbonyl index, the unsaturation decreases, the smoke point and the viscosity changes. . There are commercial devices to detect one or more changes in the oil that occur with use, and each of these methods has its own drawbacks. For example, the FOODOIL-SENSOR (Northern States Instrument, Circle Pines, MN) monitors the change in the dielectric constant of frying oils, but this instrument must be calibrated daily with fresh oil. Because different oils have different dielectric constants, separate information must be provided for each type of oil to determine whether the change in the dielectric constant of a particular oil indicates that the oil should be discarded. These types of instruments may not give consistent results over time, because the test is also sensitive to environmental factors, such as air currents, or is sensitive to the presence of food particles in the oil itself. The instruments do not work well in an air current, as happens in locations close to ventilation systems that circulate air. Many deep fryers are located under or close to strong air collection currents, making the test does not match their use in some restaurants. Libra Labs (Metuchen, NJ) and US Patent No. 4,349,353, to Blumenthal, describe tests to detect the presence of alkaline compounds that accumulate in used frying oils. US Patent No. 4,623,638 to Hayatsu et al ., Describes a silica gel that absorbs and desorbs polycyclic organic substances in a solution for detecting and eliminating mutagenic substances from the environment and food products.

There are colorimetric tests based on the pH of the oil. For example, the OXIFIT test (E. Merck, Darmstadt, Germany) is a colorimetric test kit that contains redox indicators that react with the total amount of oxidized compounds in the oil. The 3M Shortening Monitor (Minnesota Mining and Manufacturing, St. Paul, MN) is a strip of paper that contains a base as an indicator that changes color when the base reacts with fatty acids in the oil. There is FRITEST (E. Merck), and it is a colorimetric test kit that is sensitive to carbonyl compounds. Robern and Gray show a stain test ( Can. Inst. Food Sci. Technol. J. 14: 150, 1981) which is a colorimetric test that monitors the free fatty acid content of the oil based on the oil's pH. The diagnostic colors of the pH indicator are blue, green and yellow. Alkaline pollutants can also be detected in oils. Other colorimetric tests include those of US Patent Nos. 2,770,530; 3,030,190; 3,615,226; and 2,953,439.

Colorimetric assays can be problematic because the color indicators are due Easily visualize the background colors of the test. The colors such as yellow, pale red or pale green they can be difficult to read because the broken oil It can also be colored.

One of the factors that determines the quality of Cooking of used frying oils is the quantity of products of rupture in the oil. The amount of polar compounds in the oil is important because, for example, the presence of increasing amounts of polar compounds affect form harmful to the taste and viscosity of the oil. For example, increasing amounts of polar compounds tend to produce a less viscous oil, and this characteristic influences the oil permeability in food, for example in an apparatus of frying In general, less oil penetration is preferred in food for reasons of appearance, taste and health.

A large number of European countries have specific regulations for frying oils. Some of the European countries have laws to restrict the amount of polar materials in oils. For example, Austria, Belgium, France, Germany, Hungary, Italy, Spain and Switzerland require, depending on the country, that no more than 21% to 27% of polar compounds be used in the oils. The German government has determined that the presence of 27% of polar compounds corresponds to 0.7% of oxidized fatty acids insoluble in petroleum ether (Firestone, D. et al . "Regulation of Frying Fats and Oils" in Food Technology February 1991 , p. 90-93), and that levels above this amount are not acceptable. It is likely that other government agencies will also establish regulations and guidelines to ensure quality that require regular oil replacement.

Many users of oils sensitive to oxidation and hydrolysis employ replacement programs Routine periodic to ensure that oils maintain a Useful taste and consistency. For a restaurant or chain fast food, it is difficult to assess the quality of the oil to used cooking while we are at the restaurant premises, except for the simple observation of its color, the smell of the oil and / or the observation of the properties for frying. Some restaurants with great demands for fried products, and those with standards of Very strict quality, they can discard and replace their oils after a relatively short time, regardless of flavor or consistency A routine waste policy can be expensive A method to evaluate the oil, make it easy and Quick to use, it would save restaurants time and money required to routinely and blindly replace your oils.

Thin layer chromatography (TLC) developed originally as a method to separate lipids. The FTA implies the use of a thin layer of adsorbent (for example, silica gel) coated on a support or a solid surface such as glass, or similar. The sample to be analyzed is placed on the adsorbent, and a edge of the thin layer is exposed to a solvent that travels towards above the thin layer, separating the compounds in the sample based on their relative affinities for the solvent and for the adsorbent. Compounds can be identified by comparison of The sample separated with known patterns.

In general, the technique has excellent power resolution, and can be adapted to measure a variety of Chemical constituents in a test sample. When the TLC to determine the amount of polar compounds in oil, is place a stain of the test sample on a TLC plate and the plate is subjected to a solvent, such as petroleum ether, ether diethyl or glacial acetic acid. The solvent rises by effect wick through the adsorbent, towards the test sample. The test sample is separated based on relative affinities of the solvent and of the test sample by the reactive groups in the adsorbent coating. The less polar compounds travel along the TLC plate faster than the compounds highly polar Thus, TLC is used to detect the polar constituents in a test sample. The FTA is a relatively sophisticated technique that is generally used by Scientists in a laboratory.

The American Society of Oil Chemists It has standard methods to assess oil quality for freshly refined cooking, which include the amount of polar compounds in the oil. This method is published by the International Organization for Standardization, and is provided as the ISO 8420: 1990 (E) publication entitled "Determination of Polar Compounds Content in Animal and Vegetable Fats and Oils "(hereinafter referred to as" ISO 8420 "). Other methods to quantify the amount of polar compounds in oil include high pressure liquid chromatography (HPLC), liquid chromatography (LC), gas chromatography (GC), and Similar. The ISO 8420 method and other current procedures that quantify the amount of polar compounds in oil are complex and not practical for the kitchen staff in a Meal establishment

The trials that are commercially available At present they can have a large number of problems. Many of the methods currently available to test the quality of Oil require expensive equipment that must be calibrated regularly. These tests indirectly measure the polar compounds in the oil. For example, pH changes are an indirect measure of the amount of polar compounds in an oil. A big number of These tests require laboratory expertise and periods of Time greater than 2-3 hours.

Consequently, there is a need for time of a rapid test method that can be performed Reliable and easy way to determine the amount of compounds polar in oil. There is an additional need for a device to facilitate the realization of such method.

Summary of the invention

This invention provides a quick method for Determine polar compounds in an oil sample. This method It is not subject to environmental factors such as currents of air or the presence of particles in the oil. The results of the test occur quickly and consistently. A device that is easy to operate, and that can be used in Any environment in which hot oils are used.

The invention relates to a method for determine the presence of polar compounds in oil, which It comprises the steps of: providing a test surface that it comprises an adsorbent on a support, and a polar indicator located in a first position on the adsorbent; Put in contact a portion of the test surface with a sample of oil comprising polar compounds; and allow the front of the oil migrate beyond the first position and mobilize from that mode to polar indicator. The method of this invention can also additionally understand the steps of: taking the relationship of the distance that the polar indicator has moved over the adsorbent to the distance that the front of the oil has moved relative to a fixed point on the adsorbent, to generate an Rf value for the oil; and use the Rf value to determine the presence of polar compounds in the oil. The fixed point is preferably a portion of the test surface.

In this method, the adsorbent is selected preferably from the group consisting of silica, aluminum oxide, and cellulose, and the support is preferably selected from the group that It consists of glass, paper, aluminum and heat-resistant plastic. He oil is preferably selected from the group consisting of lard, corn oil, peanut oil, oil Canola, olive oil, palm oil, seed oil palm, coconut oil, red palm oil, and mixtures of same. In one embodiment, the polar indicator is a dye. polar, and preferably the polar dye is ESTOFIL-BLUE S-RLS (Sandoz Chemicals Export, available from Clariant Corp. Charlotte, NC), and preferably the polar indicator is a dye that has a affinity for the adsorbent less than the polar compounds in the oil, and an affinity for the adsorbent greater than oil not used.

The invention also relates to a device. for determining polar compounds in oil, comprising: a base; at least one side adjacent to the base; at least one deposit For the sample; and at least one thermoconductive support surface adapted to support at least one test surface that it comprises an adsorbent on a support and a polar indicator, in the that the test surface is in fluid communication with at least a sample tank when the oil is in the tank for the sample, the support surface forms an angle in relation to to a plane containing the base of the device, to provide a high support surface relative to the deposit of the sample, and in which the sample deposit is adapted for receive a test sample and a portion of the surface of test. The device may additionally comprise a cover, and the cover is preferably adapted to accommodate it on the device. In one embodiment, the lid comprises a part transparent, and the lid also comprises a handle.

The device can be adapted to test a single oil sample, or a plurality of oil samples. Preferably, the angle of the support surface relative to the base is around 10º to around 80º, and in a realization of the angle of the support surface in relation to the base is around 20º to around 70º. In one embodiment, the device comprises a thermally conductive material, and the device may comprise a solid block of a material heat conductor. In one embodiment, the device comprises a test surface, the test surface comprising a adsorbent on a support. Preferably, the adsorbent It also includes a polar indicator.

The device may also comprise a temperature indicator and, in one embodiment, the device It includes a heat source housed in the device.

The invention also relates to a system for determine polar compounds in oil, comprising: a thermoconducting device comprising a base, at least one sample tank adapted to contain a sample of oil comprising polar compounds, and at least one surface support adapted to support at least one test surface; in the one that the support surface forms an angle in relation to a plane which contains the base of the device, and in which the deposit for The sample is in fluid communication with the test surface when the oil is in the sample container; and at least one test surface comprising an adsorbent located on a support, in which the adsorbent comprises a polar indicator. He system can also comprise a cover adapted to cover the thermoconducting device In one embodiment, the lid comprises a transparent part, and the lid can also include a handle. He system device can be adapted to include a plurality of deposits for samples.

In one embodiment of the system, the device it has a face of the support that forms an angle in relation to a plane containing the base of the device of around 10º until around 80º. Preferably, the surface angle support relative to the base of the device is around 20º until about 70º. The device may comprise a material thermoconductor and, in one embodiment, the device comprises a solid block of a thermoconducting material. The device can further comprise a temperature indicator, and the indicator of The temperature can be included in the lid. In one embodiment, the thermoconducting device is prepared from a material selected from the group consisting of aluminum, copper, steel stainless, iron, zinc and tin.

The adsorbent used on the test surface is preferably selected from the group consisting of silica, oxide of aluminum and cellulose, and the support is preferably selected from the group consisting of glass, paper, aluminum and plastic heat resistant. The oil is preferably selected from the group consisting of lard, corn oil, oil peanut, canola oil, olive oil, palm oil, palm seed oil, coconut oil, red palm oil, and combinations thereof. In one embodiment, the device It also comprises a thermal source housed in the device. He polar indicator can be a colored polar dye, and preferably the dye has an affinity for the adsorbent less than the polar compounds in the oil, and an affinity for the adsorbent greater than unused oil. In one embodiment, the Dye is ESTOFIL BLUE S-RLS.

The invention also relates to a method for determine if an oil containing polar compounds is discarded, comprising the steps of: introducing an oil sample into a sample tank in fluid communication with an adsorbent that it comprises a polar indicator, in which the adsorbent is located on a support; allow the oil sample to migrate over the adsorbent and mobilize the polar indicator; in which the relationship of the distance that the polar indicator migrates in relation to the distance migrating the oil front is proportional to the amount of polar compounds in the oil. In one embodiment, the method further comprises heating the support. The method can also include the stage of covering the adsorbent with a lid. In this method, the adsorbent is preferably selected from the group that It consists of silica, aluminum oxide and cellulose, and the support is preferably select from the group consisting of glass, paper, aluminum, fiberglass and heat resistant plastic. In a embodiment, the oil is selected from the group consisting of lard, corn oil, peanut oil, oil Canola, olive oil, palm oil, seed oil palm, coconut oil, red palm oil, and mixtures of same. In one embodiment, the polar indicator is a polar dye. colored, and preferably the polar indicator is a dye that it has a lower adsorbent affinity than the compounds polar in the oil, and an affinity for the adsorbent greater than the unused oil In one embodiment, the dye is ESTOFIL BLUE S-RLS.

In another aspect of this invention, the invention refers to a device for determining polar compounds in a oil, which comprises: an adsorbent that covers a support that has a sample container located in the holder and a sample of polar indicator located on the adsorbent; and an adapted cover to accommodate on the sample container and on the sample of polar indicator. Preferably, the adsorbent is selected from the group consisting of silica, aluminum oxide and cellulose. Preferably, the support is selected from the group consisting of glass, paper, aluminum, fiberglass and plastic heat resistant. The polar indicator is a polar dye colored, and preferably the polar indicator is a dye that it has an affinity for the adsorbent less than the affinity of the polar compounds in the oil by the adsorbent, and in which the polar indicator has an affinity for the adsorbent greater than the unused oil

The invention further relates to a device for determining polar compounds in an oil, comprising: a base; at least one test surface comprising an adsorbent, with a polar indicator located on it, and a support, in the that the test surface forms an angle relative to the plane which contains the base; and at least one sample deposit located adjacent to the test surface, to establish a fluid communication with it when oil is present in Sample deposit. In one embodiment, the device additionally comprises a lid. Preferably, the angle of the test surface in relation to the base is around 10º up to around 80º.

Other embodiments are listed at continuation:

one.

A method to determine the presence of polar compounds in oil, which comprises the stages of:

  provide a test surface comprising an adsorbent on a support and a polar indicator located in a first position on the adsorbent;

 Put in contact a portion of the test surface with a sample of oil comprising polar compounds; Y

 allow the front of the oil migrate beyond the first position and mobilize that way to the polar indicator.

2.

He method of embodiment 1, further comprising the steps from:

  take her ratio of the distance that the polar indicator has moved over the adsorbent at the distance that the oil front has moved in relation to a fixed point on the adsorbent, to generate a Rf value for oil; Y

 use the value of Rf to determine the presence of polar compounds in the oil.

3.

He method of embodiment 2, wherein the fixed point is a portion of the test surface.

Four.

He method of embodiment 1, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide, and cellulose.

5.

He method of embodiment 1, wherein the support is selected from the group consisting of glass, paper, aluminum and plastic heat resistant.

6.

He method of embodiment 1, wherein the oil is selected from group consisting of lard, corn oil, oil peanut, canola oil, olive oil, palm oil, palm seed oil, coconut oil, red palm oil, and mixtures thereof.

7.

He method of embodiment 1, wherein the polar indicator is a colored polar dye.

8.

He method of embodiment 7, wherein the polar dye is ESTOFIL-BLUE S-RLS.

9.

He method of embodiment 1, wherein the polar indicator is a dye that has a lower adsorbent affinity than polar compounds in the oil, and an affinity for the adsorbent greater than unused oil.

10.

A device for determining polar compounds in oil, which understands:

a base;

at least one side adjacent to the base;

at least one sample deposit; Y

at least one thermoconductive support surface adapted to support at least a test surface, on which the test surface is in fluid communication with at least one sample tank when the oil is in the sample tank, the support surface it forms an angle in relation to a plane that contains the base of the device to provide a high support surface with in relation to the sample deposit, and in which the deposit for samples is adapted to receive an oil sample and a portion of the test surface.

eleven.

He device of embodiment 10, further comprising a top.

12.

He device of embodiment 11, in which the lid is adapted to accommodate on the device.

13.

He device of embodiment 12, wherein the lid comprises a transparent part

14.

He device of embodiment 12, wherein the lid comprises a handle.

fifteen.

He device of embodiment 11, adapted to test a plurality of oil samples.

16.

He device of embodiment 11, wherein the angle of the support surface in relation to the base is around 10º until around 80º.

17.

 He device of embodiment 16, wherein the angle of the Support surface in relation to the base is around 20º until about 70º.

18.

He device of embodiment 11, wherein the device comprises a thermally conductive material.

19.

He device of embodiment 18, wherein the device comprises a solid block of a thermoconducting material.

twenty.

He device of embodiment 11, further comprising a test surface, the test surface comprising a adsorbent on a support.

twenty-one.

He device of embodiment 20, wherein the adsorbent comprises also a polar indicator.

22

He device of embodiment 11, further comprising an indicator Of temperature.

2. 3.

He device of embodiment 11, further comprising a source of heat lodged in the device.

24.

A system to determine polar compounds in oil, which understands:

 a device thermoconductor comprising a base, at least one reservoir for samples adapted to contain an oil sample comprising polar compounds, and at least one support surface adapted to bear at least one test surface; in which the surface support forms an angle relative to a plane that contains the base of the device, and in which the sample container is in fluid communication with the test surface when there is oil in the deposit for samples; Y

 at least one test surface comprising an adsorbent located on a support, in which the adsorbent comprises an indicator polar.

25.

 He system of embodiment 24, further comprising an adapted cover to cover the thermoconducting device.

26.

He system of embodiment 25, wherein the lid comprises a part transparent.

27.

He system of embodiment 25, wherein the lid comprises a handle.

28.

He system of embodiment 24, wherein the device comprises a plurality of deposits for samples.

       \ newpage
    

29.

He system of embodiment 24, in which the surface angle support relative to the base of the device is around 10º up to around 80º.

30

He system of embodiment 24, in which the surface angle support relative to the base of the device is around 20º until about 70º.

31.

He system of embodiment 24, wherein the device comprises a thermoconducting material

32

 He system of embodiment 24, wherein the device comprises a solid block of a thermoconducting material.

33.

 He system of embodiment 24, wherein the device comprises also an indicator of the temperature.

3. 4.

 He system of embodiment 24, in which the device thermoconductor is prepared from a material selected from the group consisting of aluminum, copper, stainless steel, iron, zinc and tin.

35

 He system of embodiment 24, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide, and cellulose.

36.

 He system of embodiment 24, wherein the support is selected from the group consisting of glass, paper, aluminum and plastic heat resistant.

37.

 He system of embodiment 24, wherein the oil is selected from the group consisting of lard, corn oil, oil peanut, canola oil, olive oil, palm oil, palm seed oil, coconut oil, red palm oil, and combinations thereof.

38.

 He system of embodiment 24, wherein the device comprises also a heat source housed in the device.

39.

 He system of embodiment 24, wherein the polar indicator is a colored polar dye.

40

 He system of embodiment 24, wherein the polar indicator is a dye that has a lower adsorbent affinity than polar compounds in the oil, and an affinity for the adsorbent greater than unused oil.

41.

 He system of embodiment 24, wherein the dye is ESTOFIL BLUE S-RLS.

42

 A method to determine whether an oil containing is discarded polar compounds, comprising the steps of:

 introducing a oil sample in a tank for communication samples fluid with an adsorbent comprising a polar indicator, in which the adsorbent is located on a support;

 allow the sample of oil migrate on the adsorbent and mobilize the indicator polar; in which the ratio of the distance the indicator migrates polar in relation to the distance the oil front migrates is proportional to the amount of polar compounds in the oil.

43

 He method of embodiment 42, wherein the method further comprises heat the support.

44.

 He method of embodiment 43, further comprising the step of plugging The adsorbent with a lid.

Four. Five.

 He method of embodiment 42, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide and cellulose.

46.

 He method of embodiment 42, wherein the support is selected from the group consisting of glass, paper, aluminum, fiberglass and heat resistant plastic.

47

 He method of embodiment 42, wherein the oil is selected from group consisting of lard, corn oil, oil peanut, canola oil, olive oil, palm oil, palm seed oil, coconut oil, red palm oil, and mixtures thereof.

48.

 He method of embodiment 42, wherein the polar indicator is a colored polar dye.

49.

 He method of embodiment 42, wherein the polar indicator is a dye that has a lower adsorbent affinity than polar compounds in the oil, and an affinity for the adsorbent greater than unused oil.

fifty.

 He method of embodiment 49, wherein the polar dye is ESTOFIL-BLUE S-RLS.

51.

 A device for determining polar compounds in oil, which understands:

  an adsorbent covering a stand that has a sample container located in the holder, and a sample of polar indicator located on the adsorbent; Y

  a lid adapted to accommodate on the sample tank and on the Polar indicator sample.

52

 He method of embodiment 51, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide and cellulose.

53.

 He method of embodiment 51, wherein the support is selected from the group consisting of glass, paper, aluminum, fiberglass and heat resistant plastic.

54

 He method of embodiment 51, wherein the polar indicator is a colored polar dye.

55.

 He method of embodiment 51, wherein the polar indicator is a dye that has an affinity for the adsorbent less than the affinity of polar compounds in the oil for the adsorbent, and in which the polar indicator has an affinity for the adsorbent greater than unused oil.

56.

 A device for determining polar compounds in oil, which understands:

a base;

at least one test surface comprising an adsorbent, with an indicator polar located on it, and a support on which the surface test is forming an angle relative to the plane it contains base; Y

at least one sample tank located adjacent to the test surface, to establish fluid communication with her when the oil is present in the sample tank.

57.

He device of embodiment 56, further comprising a top.

58.

 He device of embodiment 56, wherein the angle of the test surface in relation to the base is around 10º up to around 80º.

Brief description of the figures

Figure 1 is a graph that correlates the percentage of polar compounds, measured by the method of ISO 8420 test, with the Rf determined according to the present invention. Rf refers to the ratio of the distance traveled by the polar indicator from a fixed point on the adsorbent or support a the distance traveled by the oil (that is, the front of the oil) from the same fixed point on the adsorbent or support.

Figure 2 is a perspective view of a first device according to this invention.

Figure 3 is a side elevation view, partially in cross section, of the device of Figure 2, and covered with a first cover according to this invention.

Figure 4 is a perspective view of the device of Figure 2, and covered with a second cover according to this invention.

Figure 5 is a perspective view of a second device according to this invention.

Figure 6 is a perspective view of the device of Figure 5, covered with a lid according to this invention.

Figure 7 is a perspective view of a third device according to this invention.

Figure 8 is a side elevation view, in cross section, of the device of Figure 7.

Detailed description of the preferred embodiments

The term "polar compounds in oil", as used herein, refers to the constituents of oils, fats, butter, and mixtures thereof, which can be determined by column chromatography under the conditions specified in ISO 8420: 1990 ( E) ( above ). Polar compounds include polar substances that appear in unused fats, such as monoglycerides, diglycerides, alcohols and free fatty acids, as well as polar transformation products formed during heating at temperatures and under conditions that normally occur during the frying of food in oil.

The term "oil", as used here, It includes oils, fats, and butter. Preferably, the oils they are liquids under the test conditions of this invention. The oils that can be studied in this method to determine the presence of polar groups include both those of natural origin as well like manufactured and synthetic oils. Synthetic oils include triglycerides or esters of polyfunctional alcohols with fatty acids. Synthetic oils can also be obtained at from polyfunctional carboxylic acids with fatty alcohols. Most natural oils (vegetable and animal sources) are triglycerides from polyfunctional alcohols (for example, glycerin) and fatty acids.

In one aspect of this invention, the invention is refers to a method to determine the presence of compounds polar in oil based on oil capacity to displace a polar indicator on an adsorbent. The adsorbent is select based on your ability to join with an indicator polar, and, for the polar indicator, to scroll through the polar compounds in the oil to join sites in the adsorbent. In this embodiment, a polar indicator is added to a adsorbent located on a solid surface. The oil is introduced on the adsorbent and allowed to migrate on the adsorbent for a sufficient time for the oil to migrate more beyond the point at which the polar indicator was added to the adsorbent, and preferably before the front of the oil feed has migrated the entire length of the adsorbent. The polar indicator is preferably a polar dye having a lower affinity for the adsorbent compared to the polar compounds in the oil, and a higher affinity for the adsorbent compared to the oil in its most recent form (i.e. oil in a quality that the user will probably buy, before a time when the oil is subjected to extreme heat). The amount of oil tested in The sample is at least sufficient to saturate the adsorbent. This that is, there is more oil present in the test sample than the volume of oil required to saturate the adsorbent on the surface solid.

Two measures can be taken on the adsorbent after the polar indicator has been mobilized by the oil. A measure is the distance that the front of the polar indicator performed with respect to a fixed point on the support or the adsorbent, such as the site where the polar indicator to the adsorbent or support, or the point at which introduced the oil onto the adsorbent or support, such as the base of the support. Another measure is the distance that the front of the oil performed with respect to the same fixed point on the adsorbent or the support. A ratio of the distance traveled by the polar indicator from a fixed point on the adsorbent or support a the distance traveled by the oil (that is, the front of the oil) from the same fixed point on the adsorbent or support, to create a value, referred to here as "Rf". The reading of Rf is a value that, when compared to a reference Rf value, is used to determine if a particular oil sample is due discard or not The expression "reference Rf value" is used here to refer to a predetermined value in relation to the state Degradative of an oil. This value can be adjusted, based on government regulations, or the value can be adjusted as a Quality assurance value for a particular restaurant or a restaurant chain.

The reference Rf value, which determines whether a particular oil sample must be discarded or not, may vary for a particular application of the oil, from one user to another, and / or depending on the government regulations imposed, of a country to another. For some European countries, it is not allowed, under laws or specific laws that refer to the security of the consumer, a percentage of polar compounds in animal oils and vegetables greater than 25%. This value can be correlated with a Rf interval for a given device, with an Rf value selected, and with a given adsorbent according to this invention. For other countries, it is known that the presence of polar compounds in Oils can affect the taste and / or color. Therefore while some regulatory agencies may set a certain threshold level, some restaurants may choose to use a threshold of Rf substantially less than what may be required by law or normative. The reference Rf value, which corresponds to a percentage of total polar compounds in the oil, you can adjust by government intervention, by user preference, or for both.

Using the methods of this invention, you can test a variety of oils of natural and synthetic origin. By For example, using these methods you can test used oils in cooking. These oils include, but are not limited to, mixtures. patented and non-patented oils used for frying food, as well as lard, corn oil, peanut oil, Canola, olive, palm oil, palm seed oil, coconut oil, red palm oil, and the like. Preferably, The oils tested in this invention have an Rf of about 0.2 to about 0.9 in its unused form, usually in its most recent way. That is, oils must include an amount enough of polar compounds to mobilize the polar indicator from its point of application to a measurable distance from the point of application, to ensure that the polar indicators Selected for use in the assay of the invention will be mobilized over a degradation interval of oil.

When oil is a solid at temperature environment, or is it too viscous to move along a substrate in a reasonable amount of time at room temperature (preferably, less than about an hour, more preferably less than about 30 minutes, and even more preferably less than about 25 minutes), the oil is It can heat. Preferably, the oil is not heated to a temperature higher than the recommended temperature for frying. Typically, this is not greater than 180 ° C, and is generally around from 160ºC to around 170ºC.

The adsorbent used in this invention is generally of the type used in layer chromatographic separations fine. Acceptable adsorbents include a variety of adsorbents that preferably do not react with the oil rehearsed That is, the oil migrates along the surface of the adsorbent evenly, displacing the polar indicator, and producing a value of Rf that is lower for unused oils, generally recent, and higher for used oils. Adsorbents Exemplary include, but are not limited to, silica, oxide aluminum, cellulose, and sugars. The adsorbent is situated preferably on, it is coated on, or covers a surface solid or support. The expressions "solid surface" and "support" are used interchangeably throughout this description. The adsorbent is preferably dry on the solid surface Preferably, the solid surface is flat, and Preferred solid surfaces include, but are not limited to, glass, paper, aluminum or other suitable metal, fiberglass, or a heat resistant plastic. If a solid surface is to be used plastic or other potentially heat-sensitive surface, the plastic solid surface must be prepared from a material that can withstand the temperature of the test method without deformation or softening noticeable. The adsorbent on a Solid surface of this invention can be prepared using methods known in the art, or can be purchased commercially. Others Suitable adsorbents on a solid surface or support include reverse phase silica, and the like. A preferred adsorbent on a support is a glass plate coated with silica (such as commercially available from Analtech Co. Newark, DE). These and other supports coated or covered with adsorbents, commercially available, such as glass plates, will They can cut in a variety of sizes and shapes, such as circles or strips, or they can be used in their commercial form available. For example, a variety of plates can be used to thin layer chromatography The expressions "test strip" or "test surface" are used interchangeably here to refer to a solid surface coated with an adsorbent. Preferably, the test strip includes an indicator stain polar created by placing a polar indicator sample on the adsorbent.

In a preferred embodiment of this invention, The polar indicator is a polar dye, such as dyes which have hydroxy groups, carboxylic acid groups, ketone groups, aldehyde groups, and the like. The polar indicators are preferably polar dyes, and polar indicators have preferably lower affinity for the adsorbent compared to the polar compounds in the oil, and greater affinity for the adsorbent compared to the oil in its unused form, generally more recent. The selected polar indicators for use in this invention are heat resistant used to practice the invention.

There are a variety of dyes that could be tested for use in this invention, and these dyes can be use in its known form and / or in a chemically modified form such as the chemical modifications that include, but not limited to, sulfonation, amidation, oxidation and / or hydrolysis, for increase the polarity of a particular dye. The examples of dyes that could be useful in their present form or in a Chemically modified form include dyes available with the following trade names or denominators, including but not limited to DISPERSE BLUE dyes such as dye DISPERSE BLUE numbers 23, 28, 34, 60, 79, 79: 1 and 148 that correspond to CI numbers (color index) 61545, 62065, 61510, 61104, 11345, 11344, 11124, respectively; DISPERSE RED 2, others DISPERSE RED dyes such as dye numbers 3, 19 and 92 with the CI numbers of 60507, 11130, and 60752, respectively; the DISPERSE VIOLET dyes that include dye numbers DISPERSE VIOLET 4, 6, 17, 26 and 33, which correspond to the CI numbers 61105, 61140, 60712, 62015 and 11218, respectively; REACTIVE BLUE 6 (CI number 61549); SOLVENT BLUE dyes that include, but are not limited to, the numbers of dyes SOLVENT BLUE 14 (number of CI 61555), 35 (CI number 61554), 59 (CI number 61552), 45 (ESTOFIL BLUE S-RLS, Sandoz Chemicals Export, available from Clariant Corp., Charlotte, NC), and 104 (ESTOFIL BLUE S-RBL, Clariant Corp., Charlotte, NC); SOLVENT BLUE 97; SOLVENT GREEN 3 (CI number 61565), SOLVENT YELLOW 43, and SOLVENT RED dyes such as SOLVENT RED numbers 44, 45 and 72 corresponding to IC numbers 45385, 45386 and 45370.1, respectively. A preferred polar indicator of this invention is ESTOFIL BLUE S-RLS (C_ {44} H_ {52} N_ {O} {6} S_ {2}, also known as Solvent Blue 45, or 3,3 '- [(9,10-dihydro-9,10-dioxo-1,4-anthracenediyl) dilimino] bis [N-cyclohexyl-2,4,6-trimethyl-sulfonamide), with a CAS registration number of 23552-74-1.

For easy visual determination, the indicator polar must have a color that contrasts with the color of the oil rehearsed Vivid colors are generally preferred, such as majentas or reds, and darker shades of blue or green, and Similar. Polar indicators must be thermostable (it is say, they must still be visualized and must be able to be displaced by polar compounds in the oil when they bind to the adsorbent) at least up to the test temperature, such as, for example, they must be thermostable up to at least about 180 ° C

Very little polar indicator is required for use in A given essay. For example, typically a stain of about 1 microliter (µl) of about 0.2% ESTOFIL BLUE S-RLS on the adsorbent for a strip of test of about 7 cm 2. Those skilled in the art they will recognize that the amount of polar indicator should not be so large so that it creates on the solid surface a front of polar indicator that migrates in the form of a thick blur, giving as result an inaccurate measure of the distance between the front of the mobilized polar indicator and a fixed point such as the base of the adsorbent surface or indicator application point polar. The amount of polar indicator should also not be so small so that the polar indicator cannot be detected once it has been mobilized from its point of application.

Those skilled in the art understand that there are other compounds that can be used instead of dyes Colored polar. Other polar indicator compounds that are they can mobilize from the surface of the adsorbent in the presence of Polar compounds in an oil sample include, but are not limited to: suitable fluorescent dyes that can be visualize using ultraviolet light; compounds containing amines polar, which can be visualized using silver or other compounds reagents with amines to produce a visible reaction product; or a polar protein material that can be visualized with Ninhydrin, for example.

The Rf values of an oil in a variety of degrading conditions can be drawn graphically for a particular adsorbent surface and, optionally for a design of particular device, and can be compared with the percentage of Total polar compounds in the oil as determined using ISO 8420. The results of such a graph provide a range of Rf values that correlate with a particular percentage of polar compounds to provide a threshold to discard the oil based on a predetermined pattern, such as, for example, Government regulations Figure 1 is a graph that correlates Rf values for a variety of oils using an adsorbent surface as provided in Example 1 with the percentage of polar compounds in the oil, as determined by ISO 8420. The graph indicates that there is a direct correlation between the value of Rf and the amount of compounds polar in oils.

The present invention also relates to devices to determine the amount of polar components in oil. The device preferably provides a support thermoconductor for the test surface. In a device 10 preferred, illustrated in Figure 2, the thermoconductive support is a block, preferably prepared from a solid material thermoconductor, which provides support to the test surface, and which can preferably conduct heat to the entire length of the test surface The device 10 of Figure 2 includes a base 12, sides 14, an upper face 15 and ends 20 and 22. At least a support surface 18 extends from a reservoir 24 to samples along the upper face 15 of the device 10. On the embodiment of Figure 2, the upper face 15 forms a surface support 18, and the support surface 18 preferably forms a angle relative to base 12 so that the angle of the support surface 18 is preferably around 10 ° to around 80º with respect to a horizontal plane that contains the base 12. More preferably, the angle of the support surface 18 in relation to the base it is around 20º to around 70º, and in a particularly preferred embodiment the angle is around of 30º. The angle of the support surface helps retain the oil sample in the sample tank 24, facilitates the uniform migration of the oil along a test strip 27, improves the thermal conductivity of the device, and facilitates the oil front and polar indicator display as The oil migrates along the adsorbent. As a result of the nature of the angle of the support surface 18, one end 20, closest to reservoir 24 for samples, it is shorter in height with relation to end 22. The sample container 24 may have any variety of configurations, and in the illustrated embodiment in Figure 2 the sample container 24 is formed by one or more flanges 25 extending from end 20 and from to minus a portion of sides 14. In a preferred embodiment, the support surface 18 includes a recessed face portion 26 which is parallel and that is lowered in relation to the plane formed by the support surface 18 (see cross section in Figure 3).

The invention also relates to a system that it comprises a device, according to this invention, and a surface of test. In use, it is placed on the support surface 18 of the device 10 a test surface, here a test strip 27 (Figure 2), which has an upper end 31 and a lower end 33, and comprising a solid surface or support 29 and a adsorbent 28 coated on solid surface 29. In a preferred embodiment, a polar indicator spot 30 is placed near the lower end 33 (preferably centered on the lower quarter of test strip 27). Preferably, the Polar indicator is applied to the adsorbent in a small volume, and it let dry. The polar indicator 30 can also be dispersed in the adsorbent. The polar indicator 30 is preferably applied to the minus the bottom of test strip 27, and, when the Polar indicator is deposited as a spot on the adsorbent, the polar indicator is placed on the test strip next to the 24 deposit for samples. The support surface 18 may have any variety of width dimensions, and it is at least as width as the width of the test strip 27, and preferably at less as wide as the width of adsorbent 28. Strip 27 of test can be any length, but preferably a length less than or equal to the length of the upper face 15. The test strip 27 may be longer than upper face 15, but you may not have the benefit of heat conduction that provides when there is a direct contact between the surface support 18 and test strip 27. The device 10 heats up preferably for a time in a heat source, such as a hot plate, a frying iron, or the like. He heating is not necessary when the oil is able to migrate to along the adsorbent at room temperature; However the heating can reduce the viscosity of the oil to allow evaluate solids and viscous oils to determine the presence of polar compounds in the oil. It is added to deposit 24 to shows an oil sample, preferably about 0.5 ml up to about 10 ml, and more preferably about 1 ml, Depending on the size of the sample tank. The amount of oil should be sufficient to saturate adsorbent 28. The oil hot or cold can be added in the sample tank 24. Preferably, but not required, test strip 27 is placed in the device before the oil is added. The device is incubate for a sufficient time to allow the front of the oil migrates over the test strip beyond the polar indicator, and to allow the polar indicator to move on the surface of the adsorbent if there are enough polar compounds in the sample of oil. Incubation can be performed at room temperature or at elevated temperature, as set forth above.

Device 10 is provided in section. cross section in Figure 3 located on a surface 32 heated. A cover 34 is placed on the device 10 to provide uniform heat to the oil as it migrates over the adsorbent 28. The cover 34 can have any shape three-dimensional, and preferably provides a vault cover on the device 10 while resting on a surface 32 heated, such as an iron, an oven surface, and Similary. In the device illustrated in Figure 3, the cover 34 is a substantially rectangular lid with sides 36 and a part upper 38. In Figure 4, a cover 39 is substantially circular in cross section, with a side 40 and a top 42 circular. A handle 44 is preferably included to facilitate the lid handling on heated surface 32. In a preferred embodiment, the sides of the covers of this invention are prepared from a tear resistant substance, such as Teflon, fiberglass, ceramic material, and the like, and the part top, or at least a portion of the tops of the caps of this invention, they are prepared from a substance substantially transparent heat resistant, such as a plastic heat resistant that includes, but is not limited to, polyester, Acrylic material, polycarbonate, and the like.

It will be understood that the device provided in Figure 2 can take any dimension. As noted previously, the width of the support surface 18 is wide enough to support at least one test strip that It comprises an adsorbent. It will be understood that the device may have a variety of sizes to accommodate a variety of dimensions and geometries of the test strip. The adsorbent on solid surface 29 is long enough to allow the polar indicator 30 migrates in the presence of the oil sample from the point of application of the polar indicator to provide two easily measurable points: the distance that the polar indicator has migrated relative to a fixed point (for example, the aspect bottom of the adsorbent or support, or the point of application of the polar indicator), and the distance that the front of the oil.

The test surface 27 comprises a solid surface or support 29 and an adsorbent 28 having a length of about 5 centimeters (cm) up to about 15 cm, and preferably a length of about 7 cm up to about 10 cm The support with the adsorbent has preferably a width of about 7 millimeters (mm) up to about 15 mm wide, and preferably about 10 mm wide The device 10 has a support surface 18 which is preferably at least as long as the length of the adsorbent on the support. The sample container preferably contains at least a 0.5 ml sample. The oil level in the tank for samples it is below spot 30 of the polar indicator. In a preferred device 10, the base 12 of the device has preferably a length of about 72 mm and a width of 60 mm, with a height at the end 20 of 15 mm and a height at the end 22 of about 43 mm. In a preferred device, the face angle 18 relative to the base is preferably around 30º and is generally around 20º until around of 70º. In a device with these dimensions, the test is considered terminated when the oil front has migrated to along the adsorbent material on the solid surface a distance of about 50 mm in relation to the lower end of the adsorbent material. Those of ordinary skill in the art will recognize that the dimensions of the device can be varied without undue experimentation, and that calibration (i.e., the determination of Rf threshold values for oils) of devices with different sizes can also be performed without unnecessary experimentation

Preferably, the support surface 18 is Prepares from a material that conducts heat well. The Examples of such materials include, but are not limited to, aluminum, copper, stainless steel, iron, zinc, tin and others thermoconductive materials. Preferably, the material Thermoconductor is aluminum. In a preferred embodiment, the device 10 is prepared from a thermoconductive material such like aluminum

In the device of Figure 2, and using a test strip with an adsorbent prepared from silica, a 25% threshold for the percentage of total polar compounds in fats and oils, as required by some European countries, are correlates with an Rf value of about 0.52 to about of 0.54. Restaurants in countries that require the disposal of oils with 25% of total polar compounds in the oil preferably they will discard the oil with an Rf value of at least around 0.52 to at least about 0.54.

Device 10 and other devices according to this Invention may include a variety of sensors or markers. By For example, at least one temperature sensor can be attached to the surface of the device 10 to monitor the temperature during the course of the trial period. There is a variety of temperature sensors that would be suitable with this device, including, but not limited to, devices with sensors temperature adhesives as well as a variety of devices thermosensors such as those available from Pacific Transducer Corporation (Los Angeles, CA), and the like. Similarly, it could provide a well at one end of the device that adapt to fix a thermometer, or other thermosensitive device, such as an electronic device, or the like. The experts in the technique will recognize that the temperature sensor could be placed in a variety of locations on the devices of this invention, or, alternatively, in a cover of this device.

Markers can be included in the device, such as the marks on the device to indicate when the trial is finished, for example based on the migration of the oil front In another example, when the device is sold in a country that regulates a threshold level of polar compounds in oil, the device may include brands that provide intervals for the mobility of the front of the polar indicator with relation to a mark for the front of the oil to indicate oil ranges that have an acceptable level of compounds polar in the oil. You can also include marks for levels of oil in the oil tank. Brands may have a variety of forms, including, but not limited to, brands Engravings, adhesive marks, colored marks, and the like.

In addition, the devices of this invention they can also incorporate a heat source or a thermal element so that the support surface can be heated from a internal thermal source

While Figures 2-4 illustrate a device with a single well, others are possible Settings of this device. In one embodiment, it is possible modify device 10 to include linking elements of so that a plurality of devices can be linked according to the device 10 to form a multi-well device, for simultaneous or sequential measurement of more than one sample. The Figure 5 illustrates a multi-well device 47 according to this invention, with a plurality of sample tanks. In the Figure 5, the device is substantially similar to that of Figure 2. Device 47 has a base (not shown), sides 48, a upper face 50 comprising a plurality of support surfaces 52, ends 54 and 56, a plurality of reservoirs 58 for samples, and a plurality of lowered faces 60. The flanges 60, or means equivalent, are used to separate reservoirs 58 for samples, so that oil samples do not contaminate each other at separate test strips. In this embodiment, it can be tested simultaneously or sequentially one or more oil samples. He device of Figure 5 includes 3 test strips 27 located at along each support surface 52. Optionally, you can Include a temperature sensor.

In use, as provided in Figure 6, the device 47 is placed on a heated surface 66, with at minus one test strip 27 in place. One or more are placed oil samples separately in reservoirs 58 for samples. A cover 68 is adapted to accommodate the device 47. The cover 68 is adapted with sides 70, with a top 72 and with a handle 74. Preferably, at least a portion, such as the part upper 72, of the cover 68 is transparent.

The device of this invention may have a variety of settings. For example, in another embodiment of device of this invention, illustrated in Figure 7, the device 76 comprises a test surface 78 and a cover 80. In this embodiment, the cover 80 can rest directly on test surface 78. The test surface 78 comprises a adsorbent 82 on a solid surface 84, according to this invention, and a spot of a polar indicator sample is placed, also according to this invention, preferably in a plurality of spots 83 or as a polar indicator ring, located on the adsorbent 82, preferably at least about a quarter of the distance from a reservoir 88 for samples to the point of contact between cover 80 and test surface 78. The test surface 78 is located horizontally on a surface 86 heated.

A reservoir 88 is provided for samples in fluid communication with test surface 78. Deposit 88 for samples may comprise a portion of a solid surface 84 without an adsorbent coating on it. In other embodiment, the sample container 88 may comprise a solid surface depression 84. Other configurations for the deposit 88 will be manifest for normal experts in the technique. The lid 80 is a vault-shaped device, although those of ordinary skill in the art will recognize that lid 80 can have a variety of geometries without separating from the scope of the invention. In the embodiment of Figure 7, the cover 80 has a substantially circular cross section, and includes a side 90 and a top 92. The cover 80 also optionally includes a test sample supply system, to introduce a oil sample to be tested in tank 88 for samples. In the embodiment of Figure 7, the sample delivery system of trial includes a housing to retain at least one sample of test, and means to slowly feed the oil into the tank 88 for samples, such as a dropper type device 94. When he 88 tank for samples includes a surface depression solid 84, a device 94 of type dropper or other sample supply system, since the Oil sample can be loaded directly into tank 88 For samples.

Figure 8 shows, in section transverse, the device 76. The test surface 78, which comprises an adsorbent 82 on a solid surface 84, is placed on a heated surface 86, such as an iron, a plate hot, or in an oven. A lid 80 is centered so that the dropper type device 94 is centered on the tank 88 to samples. The dropper type apparatus, in the embodiment of the Figure 7 and 8, includes a support 96 for removably holding a dropper 98 on site over reservoir 88 for samples. In the Figure 7 and Figure 8, the sample supply system also includes a means to slowly add the oil sample to tank 88 for samples. In the embodiment of Figure 7, this Medium is a 100 bulb.

Those of ordinary skill in the art will recognize that there is a variety of sample supply systems and of means for slowly introducing the oil sample through the lid 80 inside the reservoir 88 for samples. For example, it you can use a capillary tube connected through the cap to a reservoir for oil samples with a pump, such as a pump peristaltic or similar, to slowly introduce the oil into the sample. These methods for introducing oil into the tank 88 to Samples are technologies known in the art, and should not remove Merit to the spirit of this invention. Like the realizations previously described, the test surface 78 is heat resistant (i.e. non deformable), preferably up to around 170º. In the embodiments of Figs. 7 and 8, the oil migrates like a circle that is getting wider and wider away from reservoir 88 for samples. The value of Rf is calculated as a ratio of the distance that the polar indicator has migrated from a fixed point in relation to the distance that the front of the oil from the same fixed point. Preferably, the fixed point is The application point of the polar indicator sample, or the edge from reservoir 88 for samples. If necessary, you can take a plurality of measures based on the plurality of spots on the polar indicator, or based on multiple measurements of a ring of polar indicator, and can be used to create an average value of Rf.

In another configuration of a device for test the presence of polar compounds in oil, which is not illustrated here, the device includes a surface or test strip comprising an adsorbent on a solid surface with a polar indicator located near but at a distance from the edge lower adsorbent material. The test surface is placed in a substantially vertical position, in a chamber. The camera It preferably has a base, sides, and a lid. Preferably, the camera is long enough to fully contain the solid surface However, it will be understood that the surface solid can be extended from the camera just like the strip of test can be extended beyond the support surface of the Embodiments illustrated in Figs. 2 to 6. Preferably, the test surface rests in the chamber along the base of the camera, and is supported on at least two points on the sides camera internals That is, the camera can have a variety of shapes, including the cylindrical, rectangular, and similar shape. Also, preferably, the angle of the solid surface with ratio to the base of the chamber is preferably greater than 45 °. Be place an oil test sample in the bottom of the chamber a sufficient amount to come into contact and to saturate the adsorbent surface, but rising to an initial level below the spot level of the polar indicator. The camera It is preferably tightly closed, and placed preferably in a heated environment, such as in an oven, a hot plate, an iron or other heat source, during a enough time for the front of the migrating oil to mobilize to the polar indicator, and for the oil front to migrate a Measurable distance beyond the front of the polar indicator. In In effect, the oil sample in this invention is the solvent for The polar indicator. Again, the value of Rf is calculated as described above.

Another aspect of this invention relates to a kit to be supplied to people, companies, suppliers of services, and the like, that need to assess the quality of a oil containing polar compounds. The kit includes preferably a device according to this invention, at least one test strip or test surface comprising an adsorbent precoated on a solid surface and that includes an indicator polar spot previously stained on the adsorbent of each strip of test or test surface. The kit can optionally include a lid, according to this invention, a sample of pure oil for use As a control, a polar indicator sample to be added to the test strip or to the test surface, a taking device of samples to facilitate the removal of an oil sample and apply it to an oil tank of the devices of this invention, and written guides and instructions for the device and for the ranges of Rf values that correlate with the intervals in percentages of polar compounds in a sample of oil measured by a particular device. If required, a heat source with a surface can also be supplied able to be heated; however, in a preferred mode of operation, the devices of this invention are adapted to that are suitable in most restaurant kitchens, and can be used in irons and / or ovens, or alternatively they can Incorporate a heat source directly into the device.

The devices of this invention are Reusable and easily cleanable. For example, you can leave cool the device, and clean it by rubbing it. Advantageously, the test works without filtration or other stages of preparation of the oil sample

All references and publications cited here they are expressly incorporated as a reference in this description.

Example 1 Test to determine the presence of polar compounds in oils, and correlation of the test with ISO 8420

Samples were tested using the methods of this invention, and were compared with the results as determined using ISO 8420.

Oil samples : a sample of recent oil (i.e. unused oil), oil identified as used but still acceptable for frying, and oil identified as used and no longer acceptable for frying (oil that has been discarded, or is leaving to be discarded), were obtained from local fast-food restaurants, as indicated in Table 1. Unused oil was hereinafter referred to as "recent", used but still acceptable oil was identified as "in use", and the oil no longer acceptable was identified as "discarded".

In the study oil samples were used to frying collected from fast food chains (trial site A-D) in the United States of America and outside of United States (OUS). These oils were used to fry fish, chicken, chips, pies, onion rings and other types of foods. Samples were collected from fresh oil and oil that had been used for some time and that, therefore, represents oils with varying levels of degradation.

Plate preparation : A thin layer silica gel chromatography plate with glass support, commercially available from Whatman Company (Clifton, NJ) was cut as a Diamond Series K6F plate (with a 250 micrometer thick coating with a pore size of 60 angstroms and with a particle size between 10-12 micrometers), in small strips 10 mm wide by 67 mm long.

A 0.2% dye solution was prepared dissolving 200 mg of ESTOFIL dye powder S-RLS, obtained from Clariant Corp (Charlotte, NC), in 100 g of toluene A spot of one microliter of dye solution on the silica gel strip, so that the stain was centered with respect to the width of the strip and to approximately 5 mm from one end (the one designated as the base of the strip, that is, the portion of the strip that comes into contact with the deposit for samples). The stain was allowed to dry under conditions environmental.

A device was prepared according to the description of Figures 2-4. The device was prepared from of aluminum, and was 43 mm high, 72 mm long and 60 mm high width, with a support surface forming an angle relative to the base of the device of around 30º.

The aluminum block was preheated by placing it in a hot laboratory plate, set at around 170 ° C for about 30 minutes. The strip stained with the Polar indicator was placed on the block, with the base of the strip adjacent to the oil tank of the block, and with the stain of the Polar indicator at a certain distance from the tank. After 2 minutes, 1 ml of test oil was added, preferably drop to drop, in the tank, making sure that the oil does not touch directly to the polar indicator. After the oil was added, The block was covered. Once the oil front reached a distance of about 50 mm from the base of the test strip (usually between about 25 to about 35 minutes), the test strip was removed. The distance traveled by the indicator Polar was measured from the base of the test strip, and also measured the distance traveled by the front of the oil from the base of the test strip. This distance relationship traveled by the Polar indicator / distance traveled by the front of the oil is denominated Rf, and represents the level of polar compounds in the oil.

In a specific example, sample 5, was added oil obtained from a local fast food restaurant (site B) drop by drop to the tank until the oil level was just below the spot of the polar indicator, on the strip. It was used approximately one milliliter of oil. The oil level did not touch nor covered the spot of the polar indicator. This prevents the indicator polar dissolves in oil. A lid was placed on the block heat-resistant transparent, and the oil was allowed to migrate to above the strip until the oil front reached a mark in the block that designates a distance traveled of about 50 mm from the base of the strip (usually an incubation time of around 25 to about 35 minutes). The strip was removed then of the block. Using a ruler, it was determined that the distance traveled from the base by the front of the polar indicator was of about 22 mm. The distance traveled from the base by the Oil front was determined to be around 50 mm. The Rf or ratio of fronts was calculated by dividing the distance traveled by the front of the polar indicator between the distance traveled by the oil front In this example, the calculated Rf was 0.44.

Rf = \ frac {d_ {1}} {d_ {2}}

where d_ {1} is the distance that migrates the front of the polar indicator in relation to a fixed point d_ {0}, and d_ {2} is the distance that migrates the front of the oil in relation to the same fixed point d_ {0}. Preferably, the fixed point d_ {0} is the base of the test strip, or the point of indicator application polar.

ISO 8420, determination of the percentage of polar compounds: to determine the total percentage of polar compounds in the oil, a method was used, the ISO 8420: 1990 (E), "Determination of Polar Compounds Content in Animal and Vegetable Fats and Oils. "This method employs a column chromatography, and is an industry standard method to separate polar compounds from degraded frying oils or used, to quantify polar compounds in oils.

In summary, in this method it was placed, in the bottom of the column, a glass rod containing A little ball of cotton wool. The air was removed by pressing the wool Cotton down with the rod. They were added to the column about 30 ml of elution solvent (mixture of 87 volumes of light oil of chromatographic quality (range of boil 40 ° C to 60 ° C) and 13 volumes of diethyl ether stabilized).

A silica gel suspension was prepared in a 100 ml beaker using about 80 ml of elution solvent. The suspension was poured into the column using a funnel. The transfer of the silica gel in the column is completed by rinsing the beaker with the solvent of elution The stopcock was opened in the chromatographic device, and the elution solvent was passed until the solvent of elution was about 100 mm above the silica gel. He silica gel was leveled by tapping the spine, and placed a layer of sand on silica gel. Elution solvent supernatant was run up to 10 mm from the sand layer.

The test sample was weighed to the milligram nearest, and 1mg and 2.5g ± 0.1g of the sample was added assay to a 50 ml volumetric flask. The trial portion is dissolved in about 20 ml of the elution solvent by means of a slight heating. The elution solvent was allowed to cooled to room temperature, and diluted to 50 ml with elution solvent.

A 250 ml flask was dried, and the flask was weighed and placed under the column to collect the sample. To prepared column twenty milliliters of the test solution. The stopcock was opened, and the solvent will run down to the level of the top of the sand layer. Eluate (containing non-polar compounds) It was collected in the 250 ml flask. Non-polar compounds are they were allowed to elute by adding 150 ml of the elution solvent via a drip funnel. The flow rate was adjusted so that the volume of 150 ml could pass through the column in about 60 minutes Up to about 70 minutes. After finishing the elution, the material that adheres to the exit of the column was washed using elution solvent. The solvent was removed from the flask under vacuum, typically with the help of a rotary evaporator and a bath of controlled water at a temperature not exceeding 60 ° C. Was added nitrogen to the system to complete the evaporation process. He flask was weighed to the nearest milligram. Content polar compounds was determined as a given mass percentage by the formula:

\ frac {m_ {1} - (5/2) m_ {2} - m_ {3}} {m_ {1}} \ \ times \ 100

       \ newpage
    

in which m_ {1} is the mass, in grams, of the test portion, m2 is the mass, in grams, of the non-polar fraction, and m 3 is the mass, in grams, of the control from elution

The analysis of the results showed a good correlation between Rf values obtained using the methods of this invention compared to the percentage of compounds polar determined by the column chromatography method (see Figure 1). The higher the value of Rf, the higher it is % of polar compounds produced in frying oils. The results indicated that the value of Rf could be predetermined knowing the percentage of polar compounds in the oil, and, similarly, knowledge of% polar compounds in the oil allowed the determination of the Rf value of the sample.

TABLE 1 Comparison of the value of Rf with the% of compounds polar determined using ISO 8420

Sample Source Rf % of Compounds polar one Oil A: oil recent (US) 0.22 2.85 2 Oil B: recent oil (US) 0.22 2.17 3 Oil C: recent oil (OUS) 0.24 6.18 4 Oil A: used oil (in use) 0.30 10.12 5 Oil B: used oil (in use) 0.44 19.13 6 Oil C: used (fried chicken, in use) 0.54 25.60 7 Oil C: used (fried fish, in use) 0.42 18.27 8 Oil C: used (chips, in use) 0.41 15.70 9 Oil A: used (discarded) 0.53 23.19 10 Oil B: used (discarded) 0.70 36.80 eleven Oil C: used (discarded) 0.51 25.28 12 Oil D: used (fried chicken, discarded) 0.45 17.85

Figure 1 is a graph that represents the Rf data from Table 1 with% polar compounds as determined using ISO 8420: "Determination of Polar Compounds Content in Animal and Vegetable Fats and Oils ".

The correlation graph (Figure 1) demonstrates The results of this study. At the 25% level of compounds polar, the corresponding Rf is 0.53. Therefore, in the block, the distance traveled by the polar indicator in relation to the front 50mm oil (fixed) is 26.5mm. You must discard any variety of oils, according to this invention, which displace the polar indicator beyond the 26.5 mm mark on the device according to this example. When the height of the polar indicator is smaller than 26.5 mm, using a 25% cut of polar compounds, this Oil is still usable.

Those skilled in the art will appreciate that, although the invention has been described above in relation to particular embodiments and examples, the invention is not necessarily limited in this way, and that others can be performed numerous embodiments, examples, uses, modifications and deviations from the embodiments, examples and uses, without separating of the inventive scope of this application.

Claims (28)

1. A method to determine the presence of Polar compounds in oil, comprising the steps of:

provide a test surface comprising an adsorbent on a support and a polar indicator located in a first position on the adsorbent;

Put in contact a portion of the test surface with an oil that it comprises polar compounds; Y

allow the front of the oil migrate beyond the first position and mobilize that way to the polar indicator.

2. The method of claim 1, which It also includes the steps of:

take her ratio of the distance that the polar indicator has moved over the adsorbent at the distance that the oil front has moved in relation to a fixed point on the adsorbent, to generate a Rf value for oil; Y

use the value of Rf to determine the presence of polar compounds in the oil.

3. The method of claim 2, wherein the Fixed point is a portion of the test surface. 4. The method of any one of the preceding claims, further comprising heating the support. 5. The method of any one of the preceding claims, wherein the support is selected from the group consisting of glass, paper, aluminum and plastic heat resistant. 6. The method of any one of the preceding claims, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide, and cellulose. 7. The method of any one of the preceding claims, wherein the polar indicator is a colored polar dye. 8. The method of any one of the preceding claims, wherein the polar indicator is a dye that has a lower adsorbent affinity than polar compounds in the oil, and an affinity for the adsorbent greater than unused oil. 9. The method of any one of the preceding claims, wherein the oil is selected from group consisting of lard, corn oil, oil peanut, canola oil, olive oil, palm oil, palm seed oil, coconut oil, red palm oil, and mixtures thereof. 10. A device for determining compounds polar in oil, comprising:

an adsorbent covering a support that has an oil sample tank located on the support, and a sample of polar indicator placed on the adsorbent; Y

a lid adapted to accommodate on the sample tank, and a Polar indicator sample.

11. A device for determining compounds polar in oil, comprising:

a base;

at least one side adjacent to the base;

at least one sample deposit; Y

at least one thermoconductive support surface adapted to support at least a test surface comprising an adsorbent on a support and a polar indicator, on which the test surface is in fluid communication with at least one sample tank when the oil is in the sample tank, the support surface it forms an angle in relation to a plane that contains the base of the device to provide a high support surface with ratio of at least one sample deposit that is adapted to receive a sample of oil and a portion of the surface of test.

12. The device of claim 11, which additionally comprises a lid. 13. The device of claim 10 or 12, in which the lid is adapted to accommodate on the device. 14. The device of claim 13, in the that the lid comprises a transparent portion. 15. The device of claim 13, in the that the lid comprises a handle. 16. The device of any one of the claims 12 to 15, further comprising an indicator of temperature. 17. The device of any one of the claims 12 to 16, further comprising a heat source hosted on the device 18. The device of any one of the claims 12 to 17, wherein the device comprises a thermoconducting material 19. The device of claim 18, in the that the device comprises a solid block of a material heat conductor. 20. The device of claim 18 or 19, in which the thermally conductive material is selected from the group that It consists of aluminum, copper, stainless steel, iron, zinc and tin. 21. The device of any one of the claims 12 to 20, wherein the surface angle support in relation to the base is around 10º to around of 80º. 22. The device of any one of the claims 12 to 21, wherein the surface angle support in relation to the base is around 20º to around of 70º. 23. The device of claim 10 or 22, wherein the adsorbent is selected from the group consisting of silica, aluminum oxide, and cellulose. 24. The device of claim 10 or 22, in which the support is selected from the group consisting of glass, paper, aluminum, and heat-resistant plastic. 25. The device of claim 10 or 22, in which the oil is selected from the group consisting of butter Pork, Corn Oil, Peanut Oil, Canola Oil, olive oil, palm oil, palm seed oil, oil of coconut, red palm oil, and combinations thereof. 26. The device of claim 10 or 22, in which the polar indicator is a colored polar dye. 27. The device of claim 26, in the that the polar indicator is a dye that has an affinity for the adsorbent less than the polar compounds in the oil, and a affinity for the adsorbent greater than unused oil. 28. The device of any one of the claims 12 to 27, adapted with multiple deposits for test a plurality of oil samples.